The expression of the hemagglutinins of Avian influenza virus H5 H7and H9 subtypes was studied in this article by Pichia pastoris, one of the eukaryotis expression systems. Three reconstructed expression plasmids and engineering strains, named pPIC9K-H5HA, pPIC9K-H7HA, pPIC9K-H9HA and GS115/pPIC9K-H5HA, GS115/pPIC9K-H7HA, GS115/pPIC9K-H9HA repectively, were obtained. The reconstructed yeast engineering strains were identified by MD and MM plate selecting and PCR. The induced interests proteins were examined by SDS-PAGE and Western-bloting,the results showed that the interest genes were expressed exactly. And this will be helpful in the future study of antigen detection and antibody detection kit, as well in the subunit vaccines developing.
Animals ; Hemagglutinin Glycoproteins, Influenza Virus ; biosynthesis ; genetics ; Influenza A Virus, H5N1 Subtype ; genetics ; Influenza A Virus, H7N7 Subtype ; genetics ; Influenza A Virus, H9N2 Subtype ; genetics ; Pichia ; genetics ; metabolism

We produced high pathogenic avian influenza H5N1 haemagglutinin protein HA1 in recombinant Pichia pastoris in a 10 L fermentor, to establish a high-density cell fermentation method. We studied the effects of different factors such as culture temperature, induced temperature, methanol feeding methods, trace elements on the growth of Pichia pastoris, the yield and the biologic activity of recombinant HA1 protein. The culture temperature in pre-induced and induced stage were optimized at 25 degrees C to adapt cell growth and recombinant protein expression, and induced temperature at 25 degrees C also resulted in higher biologic activity of rHA1 than at 30 degrees C. The binding activity of rHA1 against a wide-spectrum neutralizing antibody was susceptible to the presence of any trace elements, although trace elements would essentially benefit for the cell fermentation. As a conclusion, the expression level of rHA1 produced with optimized fermentation process reached 120 mg/L, which was 10.5 times higher than the one produced in regular shaking flask. The resultant high-density cell fermentation can likely produce rHA1 of H5N1 in large scale.
Fermentation ; Hemagglutinins, Viral ; biosynthesis ; genetics ; Influenza A Virus, H5N1 Subtype ; genetics ; metabolism ; Pichia ; genetics ; metabolism ; Recombinant Proteins ; biosynthesis

This study aims to investigate the virological impact of the stalk region and cysteine (C) in neuraminidase (NA) of influenza A/Anhui/1/05 (H5N1) and A/Ohio/07/2009 (H1N1) viruses. The NA of A/ Anhui/1/05 (H5N1), defined as AH N1, lacked 20 amino acids (including C, defined as s20) as compared with NA of A/Ohio/07/2009 (H1N1) (defined as 09N1). We deleted s20 of 09N1 to construct 09N1-s20, and inserted s20 into AH N1 to construct AH N1+s20. To investigate the impact of C on the biological function of NA, we deleted C in 09N1 to construct 09N1-C and inserted C into AH N1 to construct AH N1-C. The pseudo-type viral particle (pp) system was used to evaluate the impact of these mutants on virology. The combination of 09N1-C and 09H1 (defined as 09H1::09N1-C) showed an infectivity 8 times that of the wild type 09H1::09N1, while the infectivity of the combination of AH N1+C and AH H5 (defined as AH H5::AH N1+C) was much lower than that of the wild type AH H5::AH N1. The infectivity of the combination of 09N1-s20 and 09H1 (defined as 09H1::09N1-s20) was 4 times that of the wild type 09H1::09N1; the infectivity of the combination of AH N1+s20 and AH H5 (defined as AH H5:: AH N1+s20) was 1/7 that of the wild type AH H5::AH N1. The co-existence of 09N1-C and AH H5 displayed 6 times the infectivity of AH H5::09N1, while the infectivity of 09H1::AH N1+C was very low. Multimer analysis showed that in the wild type 09N1, the forms of NA were dimer > tetramer > monomer; the major component of NA in 09N1-C was monomer; in 09N1-s20, the forms of NA were monomer > dimer. AH N1 was mainly composed of monomer; in AH N1+s20, the forms of NA were dimer > monomer > tetramer; in AH N1+C, the forms of NA were dimer > tetramer. Deletion of C or s20 from 09N1 did not change the expression of NA. The study suggested that deletion of C from the stalk region of NA in A/Ohio/07/2009 (H1N1) increases infectivity. Insertion of C into NA's stalk region of A/ Anhui/1/05 (H5N1) significantly decreases infectivity. Cysteine deletion in the stalk region is important for the infectivity of A/Anhui/1/05 (H5N1) and A/Ohio/07/2009 (H1N1). It may interfere with the infectivity via changes in NA polymerization.
Amino Acid Motifs ; Humans ; Influenza A Virus, H1N1 Subtype ; chemistry ; enzymology ; genetics ; pathogenicity ; Influenza A Virus, H5N1 Subtype ; chemistry ; enzymology ; genetics ; pathogenicity ; Influenza, Human ; virology ; Neuraminidase ; chemistry ; genetics ; metabolism ; Viral Proteins ; chemistry ; genetics ; metabolism ; Virulence

OBJECTIVETo prepare the 4 candidate vaccine strains of H5N1 avian influenza virus isolated in China.

METHODSRecombinant viruses were rescued using reverse genetics. Neuraminidase (NA) and hemagglutinin (HA) segments of the A/Xinjiang/1/2006, A/Guangxi/1/2009, A/Hubei/1/2010, and A/Guangdong/1/2011 viruses were amplified by RT-PCR. Multibasic amino acid cleavage site of HA was removed and ligated into the pCIpolI vector for virus rescue. The recombinant viruses were evaluated by trypsin dependent assays. Their embryonate survival and antigenicity were compared with those of the respective wild-type viruses.

RESULTSThe 4 recombinant viruses showed similar antigenicity compared with wild-type viruses, chicken embryo survival and trypsin-dependent characteristics.

CONCLUSIONThe 4 recombinant viruses rescued using reverse genetics meet the criteria for classification of low pathogenic avian influenza strains, thus supporting the use of them for the development of seeds and production of pre-pandemic vaccines.

Animals ; Chick Embryo ; Chickens ; China ; Hemagglutinin Glycoproteins, Influenza Virus ; genetics ; metabolism ; Influenza A Virus, H5N1 Subtype ; immunology ; Influenza Vaccines ; immunology ; Influenza in Birds ; prevention & control ; virology ; Neuraminidase ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Vaccines, Synthetic ; immunology

HA and M2 genes derived from human highly pathogenic avian influenza H5N1 virus (A/Anhui/ 1/2005) isolated from China, were amplified and cloned into the DNA vaccine expression vector pVRC. In order to improve the expression of hemagglutinin, the human codon usage preference was made and the whole length of HA gene of H5NI (A/Anhui/1/2005) influenza virus was synthesized,named HA/YH/K, and inserted to pVRC vector, the expression of HA/YH/K protein in eukaryotic cells was significantly improved according to internal control of actin protein. Furthermore, the M2 and HA/YH/K genes were cloned into bicistronic eukaryotic expressing vector pIRES to yield the recombinant plasmid pIRES-HA/ YH/K-M2/YS/K, which could expressed HA and M2 protein simultaneously by transfection of one plasmid. Western blot and IFA showed that the recombinant pIRES-HA/YH/K-M2/YS/K plasmid was successfully expressed in several mammalian cells (Hela, MDCK and 293FT). The above results may help to identify the function and pathogenic mechanism of HA, M2 genes derived from HPAI H5N1 (Anhui strain) and pave a way for the development of novel bivalent vaccines against human highly pathogenic avian influenza virus and for preparedness for influenza pandemic.
Animals ; Cell Line ; Gene Expression ; Genetic Engineering ; Genetic Vectors ; genetics ; metabolism ; Hemagglutinin Glycoproteins, Influenza Virus ; genetics ; metabolism ; Humans ; Influenza A Virus, H5N1 Subtype ; genetics ; isolation & purification ; metabolism ; Influenza, Human ; virology ; Recombinant Fusion Proteins ; genetics ; metabolism ; Viral Matrix Proteins ; genetics ; metabolism

The distribution of glycosylation sites in HA proteins was various among H5 subtype avian influenza viruses (AIVs), however, the role of glycosylation sites to the virus is still unclear. In this study, avian influenza H5N1 viruses with deletion of the glycosylation sites in HA were constructed and rescued by site direct mutation and reverse genetic method, and their biological characteristics and virulence were determined. The result showed that the mutants were confirmed to be corrected by HA gene sequencing and Western blot analysis. The EID50 and TCID50 tested in SPF chick embryo and MDCK cells of a mutant rSdelta158 with deletion of glycosylation site at position 158 were slight lower than that of wild type rescued virus rS, and the plaque diameter of rSdelta158 was significant smaller than that of rS. The EID50 and TCID50 of mutants rSdelta169 and rSdelta290 with deletion of glycosylation sites at position 169 and 290, respectively, were slight higher than that of wild type rescued virus rS, the plaque diameters of rSdelta169 and rSdelta290 were similar as that of rS, but the plaque numbers of rSdelta169 and rSdelta290 were 10-fold higher than that to rS. On the other hand, the rSdelta158, rSdelta169 and rSdelta290 showed similar growth rate in chicken embryo fibroblast as rS. All viruses remained high pathogenicity to SPF chickens. Therefore, the growth of AIV can be affected by changes of glycosylation sites in HA protein, by which the effect is variable in different cells.
Amino Acid Motifs ; Animals ; Cell Line ; Chick Embryo ; Chickens ; Glycosylation ; Hemagglutinin Glycoproteins, Influenza Virus ; chemistry ; genetics ; metabolism ; Influenza A Virus, H5N1 Subtype ; chemistry ; genetics ; growth & development ; metabolism ; Influenza in Birds ; virology ; Poultry Diseases ; virology

One highly pathogenic strain of avian influenza virus (AIV) was isolated from goose in China recently, designated as F-3. In order to study the viral entry mechanisms, the hemagglutinin (HA) gene of H5N1 subtype AIV isolate was amplified by RT-PCR, and then cloned into pGEM-T vector and sequenced. The sequencing result has logging in GenBank, the accession number was AY639405. The HA gene of F-3 had a complete open reading frame (ORE) and composed of 1707 nucleotides, coding for 568 amino acids. The deduced amino acid sequence at the cleavage site of the HA protein was RKKR GLF, matched to the characteristic of virulent avian influenza strain. The HA gene were subcloned into pcDNA3, so the plasmid pcDNA-HA can express the HA glycoprotein. Co-transfected pcDNA-HA, pHIT60 (include Murine Leukemia Virus structural genes, namely gag and pol) and pHIT111 (retroviral vector genome,containing LacZ as a reporter) into 293T cells. The retroviral supernatant were harvested 48 hours post-transfection, filtered through 0.45 micromol/L filter. The supernatant were used to analysis the characteristic of the pseudotyping virions by Western blotting and infection test. Western blotting revealed the HA glycoproteins can be expressed on the virions, indicated the glycoproteins were incorporated onto the retroviral virions. Infection test were performed on 293T, NIH3T3 and COS-7, all the three kinds of cells infected were lacZ positive, indicating viral entry, and revealed the pseudotype virions of MuLV-HA were infectious. So the pseudotype system of MuLV particles with AIV Hemagglutinin proteins were setted up and it can be used to study the entry of avian influenza virus isolated from goose in China.
Animals ; Cloning, Molecular ; Hemagglutinin Glycoproteins, Influenza Virus ; biosynthesis ; genetics ; Influenza A Virus, H5N1 Subtype ; genetics ; metabolism ; Leukemia Virus, Murine ; genetics ; metabolism ; Molecular Sequence Data ; Open Reading Frames ; genetics ; Recombinant Proteins ; biosynthesis ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Virion ; genetics

In order to evaluate the response to vector-expressed M1 and HA genes of influenza virus in mice, we prepared recombinant plasmid pStar-M1/HA and recombinant adenovirus Ad-M1/HA containing both the full-length matrix protein 1(M1) and hemagglutinin (HA) genes of human H5N1 influenza virus strain A/Anhui/1/2005. We then combined the DNA vaccine and adenoviral vaccine in immunization of BALB/c mice with a prime-boost regime. We immunized the mice with DNA vaccine at day 0 and 28 and with recombinant adenoviral vaccines at day 14 and 42. We took blood samples before each injection and 14 days after the final injection for detection of humoral immune responses. At day 56, we sacrificed the mice and collected splenocytes for detection of cellular immune responses. ELISA and hemagglutination inhibition (HI) assay showed that specific IgG Abs against H5N1 influenza virus was induced in serum of the immunized mice. ELISPOT results confirmed that the specific cellular immune responses were successfully induced against the M1 and HA proteins of H5N1 influenza virus. This study provides new strategy for development of novel influenza vaccines.
Adenoviridae ; genetics ; metabolism ; Animals ; Antibodies, Viral ; blood ; Hemagglutinin Glycoproteins, Influenza Virus ; genetics ; immunology ; Immunization ; Influenza A Virus, H5N1 Subtype ; immunology ; Influenza Vaccines ; immunology ; Mice ; Mice, Inbred BALB C ; Recombinant Fusion Proteins ; genetics ; immunology ; Vaccines, DNA ; immunology ; Viral Matrix Proteins ; genetics ; immunology

The M2 ion channel protein is an important target against influenza A virus. In this study, H5N1 influenza A virus M2 ion channel (H5M2) gene was cloned into pcDNA4 vector. The HEK293 stable cell line expressing H5M2 was successfully established. The expression of H5M2 ion channel protein was induced only by tetracycline and confirmed by imuunofluorescence and Western blot. The ion channel activity of H5M2 was confirmed by whole cell patch-clamp recording. Fifty micromol per liter amantadine blocked the H5M2 channel conductance completely in HEK293 cells. This stable cell line may provide a model for screening inhibitors of M2 ion channel.
Base Sequence ; Cell Line ; Humans ; Influenza A Virus, H5N1 Subtype ; metabolism ; Ion Channels ; antagonists & inhibitors ; Kidney ; cytology ; Molecular Sequence Data ; Patch-Clamp Techniques ; Viral Matrix Proteins ; biosynthesis ; genetics

Influenza vaccine strains have been traditionally developed by annual reassortment between vaccine donor strain and the epidemic virulent strains. The classical method requires screening and genotyping of the vaccine strain among various reassortant viruses, which are usually laborious and time-consuming. Here we developed an efficient reverse genetic system to generate the 6:2 reassortant vaccine virus from cDNAs derived from the influenza RNAs. Thus, cDNAs of the two RNAs coding for surface antigens, haemagglutinin and neuraminidase from the epidemic virus and the 6 internal genes from the donor strain were transfected into cells and the infectious viruses of 6:2 defined RNA ratio were rescued. X-31 virus (a high-growth virus in embryonated eggs) and its cold-adapted strain X-31 ca were judiciously chosen as donor strains for the generation of inactivated vaccine and live-attenuated vaccine, respectively. The growth properties of these recombinant viruses in embryonated chicken eggs and MDCK cell were indistinguishable as compared to those generated by classical reassortment process. Based on the reverse genetic system, we generated 6 + 2 reassortant avian influenza vaccine strains corresponding to the A/Chicken/Korea/MS96 (H9N2) and A/Indonesia/5/2005 (H5N1). The results would serve as technical platform for the generation of both injectable inactivated vaccine and the nasal spray live attenuated vaccine for the prevention of influenza epidemics and pandemics.
Animals ; Chick Embryo ; Chickens ; Genetic Engineering ; Hemagglutinins, Viral/genetics/metabolism ; Humans ; Influenza A Virus, H5N1 Subtype/*genetics/immunology ; Influenza A Virus, H9N2 Subtype/*genetics/immunology ; Influenza Vaccines/*genetics/metabolism ; Influenza in Birds/immunology/virology ; Influenza, Human/immunology/*prevention & control/virology ; Neuraminidase/genetics/metabolism ; Transgenes ; Vaccines, Attenuated/*genetics/metabolism ; Viral Proteins/genetics/metabolism